Oxidatively stable alkylbiphenyls and terphenyls as non-spreading lubricants



United States Patent U.S. Cl. 260-612 6 Claims ABSTRACT OF THEDISCLOSURE Non-spreading lubricants and fluids which are oxidativelystable as low and high temperatures and comprising a mono ordi-sec-butyl-biphenyl or terphenyl or mono ordi-sec-butyl-methoxybiphenyl or methoxyterphenyl.

The invention described herein may be manufactured, used and licensed byor for the Government for governmental purposes without the payment tous of any royalties thereon.

This invention is a continuation-in-part of our copending patentapplication, Ser. No. 568,680, filed July 28, 1966, assigned to the sameassignee hereof, now U.S. Pat. No. 3,426,076, and relates to fluids andlubricants and more particularly concerns new and improved nonspreadingfluids which are stable to oxidation.

Many nonspreading fluids are useful as lubricants in applications suchas watch mechanisms, clocks and fuzes where a continual supply oflubricating substance cannot readily be provided and where the lubricantfilm is placed between components having low relative speeds such thatthe resistance of the lubricant to spreading governs the accuracy of themechanisms. Since the non-spreading component of such nonspreadinglubricant is an important factor contributing to the performance of thelubricant, control of the nonspreading ingredient will usually lead tocontrol of the compounded lubricant. Prior art researchers havecompounded lubricants from blends containing a nonspreading ingredientcomprising a diester made from an aromatic alcohol and a dibasic acid,having the general formula:

where X and R are aliphatic (straight or branch chain) groups: X havingup to 4 carbon atoms, R having up to 5 carbon atoms, and M is 5 through7. The lubricant would normally contain a suitable oxidative inhibitor,among other possible additives. Since addition of oxidation inhibitorsto fluids can change the physical properties thereof e.g., freezingpoint, and since aromatic compounds do not respond well to antioxidants,it would be advantageous if a nonspreading fluid which is also stable tooxidation could be provided.

It is therefore an object of this invention to provide improvednon-spreading lubricants.

Another object of the invention is to provide improved nonspreadinglubricants which are stable to oxidation up to at least 100 C.

Other objects and features of the invention will become apparent as theinvention is more fully hereinafter disclosed.

In accordance with these objects it has been discovered ice that a monoor di-sec-butyl-biphenyl or terphenyl or mono ordi-sec-butyl-methoxybiphenyl or methoxyterphenyl will provide anonspreading oxidatively stable fluid. The alkyl group or groups areattached to the ring through a tertiary carbon atom. Examples ofstructures of this type are as follows:

BIPHENYL RI! RI! 0-TERPHENYL m--TERPHENYL R=sec-butyl R=sec-butyl,hydrogen, or methoxy R"=sec-butyl or hydrogen Since the higher thesymmetry of a substituted biphenyl or terphenyl the higher the meltingpoint, it is important that the compounds be as unsymmetrical aspossible in order to obtain liquids. For example,4,4-di-secbutyl-biphenyl is a liquid yet 4,4-dibutylbiphenyl (M.P. 585C.) and 4,4'-di-tert-butylbiphenyl (M.P. 128.5 C.) are solids.Therefore, substituted and unsubstituted biphenyls and terphenyls werereacted with sec-butyl chloride to form liquid sec-butyl derivativeswhich were unsymmetrical compounds.

In Table I below, spreading data are presented for our nonspreadingoxidatively stable fluids, the data being obtained at room temperatureunder anhydrous conditions.

1 Evaporated, 2 Compound 1s a known spreading fluid and is presented forcomparison purposes.

Despite the high boiling point of 4-sec-butylbiphenyl (107 C. at 0.7mm.), it completely evaporated within about 4 days leaving no residue onthe disk on which it was being tested. This compound would be usefultherefore in closed systems. While a drop of 4-S of 4-sec-butyl-4'-methoxybiphenyl only spread 0.9% after 30 days, its volume hadnoticeably decreased indicating that this compound (B.P. 146 C. at 0.7mm.) was also evaporating but at a much slower rate.

Spreading of an oil was determined in the following manner: One inchdiameter disks of Wd 52-100 steel, hardened to Rockwell C-62, werepolished successively with 0, 2/0, 3/0, and 4/0 every paper, washedunder warm tap water while being scrubbed with cotton gauze, then washedwith distilled water followed by redistilled methanol. The disks werethen dried by clean dry air. To determine cleanliness, a drop ofredistilled methanol was placed on the surface of each disk. Completeand uniform evaporation indicated surfaces acceptable for these tests. Adrop of the oil to be tested, 1 to 2 mm. in diameter, was placed on eachdisk by means of platinum wire. The degree of spreading was obtained bymeasuring the change in diameter after 7 and 30 days, respectively,using a traveling microscope.

Our nonspreading fluids may be prepared as follows:

4-sec-butyl-4'-methoxybiphenyl and 3,4-di-sec-butyl-4'-methoxybiphenyl.p-Phenylsanisole (0.25 mole, 46 gms.) was dissolved in700 ml. of hot heptane contained in a 1000 cc. four-necked flask, fittedwith a stirrer, reflux condenser, thermometer and dropping funnel.Fourteen grams of anhydrous aluminum chloride was then added. Thesolution was heated, and while maintaining a temperature at 75-85 C.,0.27 mole (25 gms.) 2-chlorobutane was added dropwise over a period of2.5 hours. After addition was complete, stirring was continued for anadditional 5.5 hours, the temperature being maintained at 75 -85 C. Thereaction mixture was poured over an equal volume of cracked ice andstirred vigorously to decompose the aluminum chloride complexes. Theorganic layer was washed free of acid with distilled water. Theunreacted p-phenylanisole was removed by distillation using a steamcondenser. The remaining mixture was distilled in a molecular pot stillto separate the product from solids and tarry products. The liquid wasthen fractionated using a vigreux column to yield both4-sec-butyl-4'-methoxybiphenyl (B.P. 137 C. at 0.65 mm.) and 3,4di-sec-butyl-4-rnethoxybiphenyl (B.P. 162 at 0.75 mm.). Both compoundswere then fractionated for further purification using a vigreux columnuntil the distillation range was less then 2 C.

4-sec-butyl-m-terphenyl and 4,4" di-sec-butyl-m-terphenyl.--m-Terphenyl[0.43 mole (100 grams)] was dissolved in 100 ml. of warm carbondisulfide contained in a 500 ml. four-necked flask, fitted with astirrer, reflux condenser, thermometer, and dropping funnel. Thesolution was cooled to C. and 7 grams (0.05 mole) of anhydrous aluminumchloride were then added. Maintaining the temperature at 0 C., 40 grams(0.43 mole) of 2- chlorobutane was added dropwise over a period of 1.5hours. After addition was complete, stirring was continued for anadditional 4.5 hours, the temperature being maintained at 0 C. Thereaction mixture was poured over an equal volume of cracked ice andstirred vigorously to decompose the aluminum chloride complexes. Theorganic layer was washed free from acid with 10% potassium carbonate,washed with distilled water until neutral to pH paper, dried overanhydrous sodium sulfate, and filtered. Carbon disulfide was removedunder reduced pressure. Unreacted m-terphenyl was removed using a steamcondenser. The products were separated by fractionation in vacuo using avigreux column to yield two liquid products. The lower boiling fractionwas identified as 4-secbutyl-m-terphenyl, B.P. 182 C. (0.3 mm.), 11.2%yield (13.7 grams). Calculated for 0 1-1 C, 92.26; H, 7.74; M.W., 286.Found: C, 92.30; H, 8.03; M.W., 289. The high boiling fraction wasidentified as 4,4"-di-sec-butyl-mterphenyl, B.P. 213 C. (0.4 mm.), 11.4%yield (16.7 grams). Calculated for C H C, 91.17; H, 8.83; M.W., 342.Found: C, 91.11; H, 8.99; M.W., 335.

4-sec-butyl-o-terphenyl and 4,4" di sec butyl-o-terphenyl.The reactionwas performed in the same manner and at the same temperature as for thepreparation of the above two compounds, employing 100 grams (0.43 mole)of o-terphenyl, 40 grams (0.43 mole) of 2-chlorobutane, 7 grams (0.05mole) of anhydrous aluminum chloride, and 100 ml. of carbon disulfide.Addition of 2-chlorobutane was done over a 1.5 hour period, and thetotal reaction time was 7 hours. Sec-butyl-o-terphenyl [B.P. 183-85 C.(0.3 mm.)] was obtained in 20.9% yield (27 grams). Calculated for C H C,92.26; H, 7.74; M.W. 286. Found: C, 92.22; H, 7.85; M.W., 295.4,4"-di-sec-butyl-o-terphenyl was obtained in 7.0% yield (10 grams).Calculated for C H C, 91.17; H, 8.83; M.W., 342. Found: C, 91.53; H,8.81; M.W., 340.

4-sec-butyl 2" methoxy-p-terphenyl.2-methoxy-pterphenyl [0.092 mole (24grams)] was dissolved in 500 ml. of hot heptane contained in a 1000 ml.four-necked flask, fitted with a stirrer, reflux condenser, thermometerand dropping funnel. Five grams of anhydrous aluminum chloride were thenadded. The solution was heated, and while maintaining a temperature at-85 C., 0.094 mole (8.7 grams) chlorobutane was added dropwise over a 1hour period. After addition was complete, stirring was continued for anadditional two days. Completion of the reaction was indicated by thefact that hydrogen chloride stopped evolving rapidly, and, upon coolingto room temperature, unreacted Z-methoxy-p-terphenyl no longercrystallized out of solution. Fractionation of the reaction mixtureyielded three products, one of which was the4-secbutyl-2"-methoxy-p-terphenyl [B.P. 181 C. (0.16 mm.)] was obtainedin 23.9% yield (7 grams). Calculated for C H O; C, 87.30; H, 7.64; O,5.05; M.W., 316. Found: C, 86.99; 0, 5.09; M.W., 306. The other twoproducts obtained were a solid isomer anddi-sec-butyl-2-methoxy-pterphenyl.

The reactant 2-methoxy-p-terphenyl (M.P. 223 C.) was prepared by a diazoreaction similar to that described for 2-methoxy-4'-bromobiphenyl(Adams, R.; Bachman, W. E.; Fieser, L. F.; Johnson, J. R.; Snyder, H.R., Organic Reactions, R. Adams ed., vol. II, p. 246, Wiley, New York,1944) employing 1.25 moles (211 grams) of 4- aminobiphenyl and 4.6 moles(497 grams) of anisole.

In the table below, some oxidation rates of our inventive nonspreadingcompound are represented. As can be readily observed from the table,there is very little oxygen uptake even after hours.

TABLE II.OXIDATION RATES AT 100 C.

(Moles oxygengmole compound/hr. X10

Initial rate Final rate (during (durin Compound 535 hrs.) 65-100 hrs.

4-sec-buty1biphenyl 0. 03 0. 03 4,4-di-sec-butylbiphenyl 0. 13 0. 174-sec-butyl-4-methoxybiphenyl 0. 00 0. 003,4-disec-butyl-4-methoxybiphen 0. 12 0. 20 4-sec-butyl m-terphenyl 0.00 0. 00 4,4-di-sec-butyl-m-terphenyl. 0. 32 0. 214-sec-butyl-o-terphenyl 0. 00 0. 00 4,4"-di-sec-butyl-o-terphenyl 0. 300. 23 4-sec-butyl-2-methoxy-p-terphenyl 0. O0 0. 00

5 off so that 0.1 to 0.5 cm. of pressure remained. Oxygen consumptionwas calculated as moles or oxygen per mole of compound.

We claim:

1. A nonspreading fluid oXidatively stable at elevated temperatures forextended periods, said fluid being selected from the group consisting of4-sec-butyl-m-terphenyl, 4,4"-di-sec-butyl-m-terphenyl,

4 sec-butyl-o-terphenyl, 4,4 di-sec-butyl-o-terphenyl, and4-sec-butyl-2"-methoxy-p-terphenyl.

2. A nonspreading fluid as described in claim 1, said fluid being4-sec-buty1-m-ter-phenyl.

3. A nonspreading fluid as described in claim 1, said fluid being4,4"-di-sec-butyl-m-terphenyl.

4. A nonspreading fluid as described in claim 1, said fluid being4-sec-buty1-o-terphenyl.

5. A nonspreading fluid as described in claim 1, said fluid being4,4"-di-sec-butyl-o-terphenyl.

6. A nonspreading fluid as described in claim 1, said 5 fluid being4-sec-butyl-Z"-rnethoxy-p-terphenyl.

References Cited Mahoney et 211.: W.A.D.C. Technical Report, 59-173BERNARD HELFIN, Primary Examiner U.S. Cl. X.R. 260-668

